Loans and Allowance for Loan Losses - Summary of Aging of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2021		Dec. 31, 2020
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	$ 28,385		$ 40,541
Current	1,364,951		1,165,235
Total	1,393,336	[1]	1,205,776	[2]
Accruing	0		0
30-59 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	17,718		24,890
60-89 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	6,558		8,773
91+ [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	4,109		6,878
Recreation [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	25,193		34,983
Current	880,004		732,391
Total	905,197	[1]	767,374	[2]
Accruing	0		0
Recreation [Member] | 30-59 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	16,603		22,058
Recreation [Member] | 60-89 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	5,525		7,582
Recreation [Member] | 91+ [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	3,065		5,343
Home Improvement [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	1,309		1,201
Current	399,712		335,684
Total	401,021	[1]	336,885	[2]
Accruing	0		0
Home Improvement [Member] | 30-59 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	794		813
Home Improvement [Member] | 60-89 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	355		218
Home Improvement [Member] | 91+ [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	160		170
Commercial Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	74		75
Current	72,014		65,265
Total	72,088	[1]	65,340	[2]
Accruing	0		0
Commercial Loans [Member] | 60-89 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due			973
Commercial Loans [Member] | 91+ [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	74		75
Medallion [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	1,809		4,282
Current	13,126		31,871
Total	14,935	[1]	36,153	[2]
Accruing	0		0
Medallion [Member] | 30-59 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	321		2,019
Medallion [Member] | 60-89 [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	678
Medallion [Member] | 91+ [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	810		1,290
Strategic Partnership [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current	95		24
Total	95	[1]	24	[2]
Accruing	0		$ 0
Strategic Partnership [Member] | 91+ [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Past Due	$ 0

[1] Excludes loan premiums of $685 resulting from purchase price accounting and $25,658 of capitalized loan origination costs.

[2] Excludes loan premiums of $2,717 resulting from purchase price accounting and $21,345 of capitalized loan origination costs.